Field of the Invention
The present invention relates to a surface treatment agent and a surface treatment method, and particularly relates to a surface treatment agent and a surface treatment method preferably applicable to surface treatment of a treatment target such as a substrate to be used in semiconductor integrated-circuit production.
Related Art
In the production of semiconductor devices and the like, lithography technology is applied prior to conducting processing such as etching on a substrate. With this lithography technology, a photosensitive resin composition is used to provide a photosensitive resin layer on the substrate, then this is selectively irradiated with and exposed to actinic radiation, and a developing process is performed, thereafter, the photosensitive resin layer is selectively dissolved and removed to form a resin pattern on the substrate. Then, an inorganic pattern is formed on the substrate by performing an etching process using this resin pattern as a mask.
Incidentally, in recent years, trends toward higher integration and miniaturization of semiconductor devices have grown, and thus progress toward refinement and higher aspect ratios of the inorganic pattern produced using a resin pattern as a mask and etching processes have advanced. In the meantime, however, a problem of so-called pattern collapse has arisen. This pattern collapse is a phenomenon in which when several resin patterns and inorganic patterns are formed on a substrate in parallel, adjacent patterns close in so as to lean on one another, and the patterns are damaged and peeled off from the base depending on the situation. If such pattern collapse occurs, the desired product will not be obtained, thereby causing a decline in the yield and reliability of the product.
This pattern collapse is known to occur when drying a cleaning liquid in a cleaning process after pattern formation, due to the surface tension of this cleaning liquid. In other words, when the cleaning liquid is removed in a drying step, stress based on the surface tension of the cleaning liquid has an effect between patterns, whereby pattern collapse occurs.
Consequently, numerous experiments have been carried out so far to prevent pattern collapse by adding a substance, which causes the surface tension to decrease, to the cleaning liquid. For example, a cleaning liquid to which isopropyl alcohol is added, a cleaning liquid to which a fluorine-based surfactant is added, and the like, have been proposed (refer to, for example, Patent Documents 1 and 2).
In addition, although not the same as pattern collapse, in order to improve adhesion between the resin pattern as the mask and the surface of the substrate to prevent a partial loss of the resin pattern by a chemical developing solution, hydrophobization treatment (silylation treatment) using hexamethyl disilazane (HMDS) has been being performed on the surface of the substrate before providing the substrate with a photosensitive resin layer (refer to, for example, “Background Art” of Patent Document 3).
Patent Document 1: Japanese Unexamined Patent Application, Publication No. H6-163391
Patent Document 2: Japanese Unexamined Patent Application, Publication No. H7-142349
Patent Document 3: Japanese Unexamined Patent Application (Translation of PCT Application), Publication No. H11-511900